Question

Select perpendicular lines from the given pair of lines :

Select one:

a.
y = − 3x + 7, y = 3x + 11


b.
y = 3x + 7, y = x / 3 + 11


c.
y = − 3x + 7, y = x / 3 + 11


d.
y = − 3x + 7, y = − x / 3 + 11

Answer 1

The line pairs that are pendicular are shown in option c.

c. y = − 3x + 7, y = x / 3 + 11

Explanation:

Perpendicular lines have slopes that are the negative inverse of each other. For example, a line with slope of 5 would have a line perpendicular to it if the second line has a slope of -(1/5) [the negative inverse of +5].

Cmpare the slopes of each pair of linear equations:

a. -3 and 3 The negative inverse of -3 would be (1/3), not 3. These lines are not perpendicular.

b. 3 and (1/3). The negative inverse of 3 would be -(1/3), not (1/3). These lines are not perpendicular.

c. -3 and (1/3). The negative inverse of -3 would be (1/3). These lines are perpendicular.

d. -3 and (-1/3). The negative inverse of - 3 would be (1/3). These lines are not perpendicular.